JP2012088470A - Method for manufacturing liquid crystal display element, and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element which has improved reliability by suppressing the secular change in voltage between a pair of substrates (electrodes) while reducing the cost, and to provide a method for manufacturing the same.SOLUTION: The method for manufacturing a liquid crystal display element including a liquid crystal layer interposed between a pair of substrates facing each other and alignment films disposed between the pair of substrates and the liquid crystal layer, includes steps of: forming a first alignment film having a straight alkyl chain on one substrate by an application process; and forming an inorganic alignment layer 15 on the other substrate by a vacuum process and then subjecting the inorganic alignment layer 15 to surface treatment by a silane coupling agent to form a second alignment film 13. The step of forming the second alignment film 13 includes a step of subjecting the inorganic alignment layer 15 to surface treatment by a first silane coupling agent having a straight alkyl chain and a subsequent step of subjecting the inorganic alignment layer to surface treatment by a second silane coupling agent having a straight alkyl chain and one hydrolyzable group.

Description

  The present invention relates to a method for manufacturing a liquid crystal display element and a liquid crystal display element.

  Conventionally, liquid crystal panels are used in many display bodies (display devices) such as televisions, monitors, and cameras. In a liquid crystal panel (liquid crystal display device), a pixel electrode and a common electrode are formed on a pair of substrates, a liquid crystal layer is sandwiched between the electrodes, and the inner surface side of each substrate, that is, the liquid crystal layer side of each electrode, An alignment film is formed.

The liquid crystal panel having such a structure is required to improve various characteristics, but increasing its reliability is also an issue. In particular, a liquid crystal panel used in a projector needs to be driven with high brightness under a high temperature environment, and in recent years, a product in which an alignment film is formed of an inorganic material such as SiO ₂ has been commercialized to cope with this. . As a method for forming an alignment film made of an inorganic material such as SiO ₂ , it is generally performed by a vacuum process using a vacuum apparatus such as oblique deposition.

By the way, with respect to an alignment film made of such an inorganic material, for example, for the purpose of improving its durability, it has been proposed to alkylate the surface of the SiO ₂ film with a silane coupling agent (for example, Patent Documents). 1, see Patent Document 2).
In recent years, for the purpose of cost reduction, the alignment film of one of the pair of substrates is formed of an inorganic material film by a vacuum process, but the other alignment film is SiO ₂ having an alkyl chain. A method of forming by a coating process using a system coating material has also been proposed (see, for example, Patent Document 3).

JP 2008-83325 A JP 2010-20093 A JP 2009-223139 A

  However, when one alignment film is formed by a vacuum process and the other alignment film is formed by a coating process as in Patent Document 3, the alignment film is different between a pair of substrates, so that a charged state is generated between these alignment films. This causes a difference in voltage between the substrates (between the electrodes). As a result, a bias is applied to one of the electrodes, and the display characteristics change with time, thereby impairing reliability.

  The present invention has been made in view of the above circumstances. The object of the present invention is to suppress the voltage change with time between a pair of substrates (between electrodes) while reducing the cost, and to improve reliability. An object of the present invention is to provide an enhanced liquid crystal display device and a method for manufacturing the same.

As a result of intensive studies to achieve the above object, the present inventor has obtained the following knowledge.
The voltage changes over time between a pair of substrates (between electrodes) because the ionic impurities gradually accumulate on one alignment film side due to the difference in alignment film between the substrates, thereby accumulating charges. It is considered that a difference in charged state occurs between the alignment films.

The reason why the ionic impurities gradually accumulate in this way is that the SiO ₂ film is formed by a vacuum process, and then the surface of this SiO ₂ film is alkylated with a silane coupling agent to form an alignment film. At this time, it was considered that many silanol groups remained on the surface of the SiO ₂ film. That is, the remaining silanol group became an active site, and ionic impurities reacted and adhered thereto, and as a result, it was considered that charges were accumulated.

Therefore, the method for manufacturing a liquid crystal display element according to the present invention includes a liquid crystal layer sandwiched between a pair of opposing substrates, and an alignment film is provided between the pair of substrates and the liquid crystal layer. A manufacturing method of
Forming a first alignment film having a linear alkyl chain on the liquid crystal layer side of one of the pair of substrates by a coating process;
An inorganic alignment layer is formed on the liquid crystal layer side of the other of the pair of substrates by a vacuum process, and then the inorganic alignment layer is surface-treated with a silane coupling agent to form a second alignment film. A process,
The step of forming the second alignment film includes a step of surface-treating the inorganic alignment layer with a first silane coupling agent having a linear alkyl chain, and thereafter having a linear alkyl chain, and And a surface treatment with a second silane coupling agent having only one hydrolyzable group.

According to this method for manufacturing a liquid crystal display element, the inorganic alignment layer formed by the vacuum process is surface-treated with the first silane coupling agent, and then the second silane coupling having only one hydrolyzable group. since forming the second alignment film surface treated with agents, for example, by surface treatment with a first silane coupling agent in the inorganic alignment layer made of SiO ₂ film, still many silanol groups on the surface of the SiO ₂ film Even then, since the surface treatment is performed with the second silane coupling agent, the remaining silanol groups as active sites may be sufficiently reduced by reacting the second silane coupling agent with the remaining silanol groups. it can.

In addition, when the first silane coupling agent has a plurality of hydrolyzing groups, the first silane coupling agent includes a hydrolyzing group different from the hydrolyzing group that has reacted with the silanol group on the surface of the SiO ₂ film. Since it has a decomposable group, this hydrolyzable group may be a new silanol group. However, since the second silane coupling agent reacts with such a silanol group derived from the first silane coupling agent, it is possible to reduce the residual silanol group serving as an active site.
Furthermore, since the second silane coupling agent has only one hydrolyzing group, this hydrolyzing group reacted with the silanol group on the SiO ₂ film surface or the silanol group derived from the first silane coupling agent. Later, no new silanol group derived from the second silane coupling agent is formed.
Therefore, many silanol groups remain in the second alignment film, and it is possible to suppress the voltage change with time between the pair of substrates (between the electrodes) due to this.

In the method for producing a liquid crystal display element, the carbon number of the linear alkyl chain of the second silane coupling agent may be less than the carbon number of the linear alkyl chain of the first silane coupling agent. preferable.
In this way, the second silane coupling agent easily reacts and adheres to the inorganic alignment layer without causing steric hindrance to the first silane coupling agent attached to the inorganic alignment layer. .

Moreover, in the manufacturing method of the liquid crystal display element, the treatment temperature in the step of surface treatment with the second silane coupling agent is lower than the treatment temperature in the step of surface treatment with the first silane coupling agent. It is preferable.
In this way, when the surface treatment is performed with the second silane coupling agent, the compound derived from the first silane coupling agent is prevented from being detached from the inorganic alignment layer.

The liquid crystal display element of the present invention is a liquid crystal display element comprising a liquid crystal layer sandwiched between a pair of opposing substrates, and an alignment film provided between the pair of substrates and the liquid crystal layer,
A first alignment film having a linear alkyl chain formed by a coating process is provided on the liquid crystal layer side of one of the pair of substrates, and the other of the pair of substrates has the first alignment film. It has a second alignment film on the liquid crystal layer side,
In the second alignment film, an inorganic alignment layer formed by a vacuum process is surface-treated with a first silane coupling agent having a linear alkyl chain, and then has a linear alkyl chain and is hydrolyzed. It is characterized by being surface treated with a second silane coupling agent having only one decomposing group.

According to this liquid crystal display element, the inorganic alignment layer formed by the vacuum process is surface-treated with the first silane coupling agent, and then the surface treatment with the second silane coupling agent having only one hydrolyzable group. Since the second alignment film is formed, the second alignment film has a sufficient number of residual silanol groups serving as active sites.
Moreover, since the 2nd silane coupling agent has reacted also with respect to the silanol group derived from the 1st silane coupling agent, the residual silanol group used as an active site has decreased.
Furthermore, since the second silane coupling agent has only one hydrolyzing group, this hydrolyzing group reacted with the silanol group on the SiO ₂ film surface or the silanol group derived from the first silane coupling agent. Later, a new silanol group derived from the second silane coupling agent is not formed.
Therefore, a large number of silanol groups remain in the second alignment film, and the change in voltage with time between the pair of substrates (between the electrodes) due to this is suppressed.

It is side sectional drawing which shows an example of the liquid crystal display device which concerns on this invention. (A) is a sectional side view showing a schematic configuration of the counter substrate, and (b) is a schematic diagram. (A) is a sectional side view showing a schematic configuration of an element substrate, and (b) is a schematic diagram. (A)-(c) is manufacturing process explanatory drawing of a 2nd alignment film. It is a graph which shows an experimental result.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the scale is different for each member in order to make each member recognizable on the drawing.

  FIG. 1 is a side sectional view showing an example of a liquid crystal display device according to the present invention, and reference numeral 1 in FIG. 1 denotes a liquid crystal display device. This liquid crystal display device 1 has a large number of liquid crystal display elements, and is sandwiched between an element substrate 10, a counter substrate 20 disposed so as to face the element substrate 10, and the pair of substrates 10 and 20. The liquid crystal layer 30 is provided. The liquid crystal display device 1 is a transmissive type, and the counter substrate 20 side is a light incident side, and the element substrate 10 side is a light emission side.

  The element substrate 10 is based on a transparent substrate 10A, which is the other substrate in the present invention, and is an active matrix type. The element formation layer 11 is provided on the liquid crystal layer 30 side of the transparent substrate 10A. Although the detailed structure of the element formation layer 11 is not illustrated, the element formation layer 11 includes a switching element such as a thin film transistor (TFT), various wirings such as a data line and a scanning line, and the like. The TFT is electrically connected to an image signal supply source via a data line, and is electrically connected to a control signal supply source via a scanning line.

  A plurality of island-shaped pixel electrodes 12 made of ITO are formed on the element forming layer 11 on the liquid crystal layer 30 side, and these pixel electrodes 12 are electrically connected to the TFT. A second alignment film 13 is provided on the element formation layer 11 so as to cover the pixel electrode 12. A polarizing plate 14 is provided on the opposite side of the transparent substrate 10 </ b> A from the liquid crystal layer 30.

  The counter substrate 20 is based on a transparent substrate 20A as one substrate in the present invention. A common electrode 21 made of ITO is provided on the liquid crystal layer 30 side of the transparent substrate 20A, and a first alignment film 22 is provided on the liquid crystal layer 30 side of the common electrode 21. A polarizing plate 23 is provided on the opposite side of the transparent substrate 20 </ b> A from the liquid crystal layer 30.

In the liquid crystal display device 1 having such a configuration, the element substrate 10 and the counter substrate 20, one pixel electrode 12, a part of the common electrode 21 corresponding thereto, and a part of the pixel electrode 12 and the common electrode 21. The liquid crystal display element of the present invention is formed by the second alignment film 13, the liquid crystal layer 30, and the first alignment film 22 disposed between the two.
The second alignment film 13 and the first alignment film 22 control the alignment of the liquid crystal molecules of the liquid crystal layer 30 and will be described in detail later.

  In the liquid crystal display device 1, when a control signal is transmitted to the TFT of the element formation layer 11, this is turned on, and an image signal is transmitted to the pixel electrode 12. Then, an electric field corresponding to the image signal is applied between the pixel electrode 12 and the common electrode 21, and the azimuth angle of the liquid crystal molecules is controlled by this electric field. Light incident from the counter substrate 20 in such a state becomes linearly polarized light by the polarizing plate 23 and is modulated by the liquid crystal layer 30 to change the polarization state. A part of the modulated light is absorbed by the polarizing plate 14 in accordance with the polarization state, becomes light having a predetermined gradation, and is emitted from the element substrate 10 side.

  The first alignment film 22 on the counter substrate 20 side is an alignment film that does not have a specific azimuth angle as shown in FIG. 2A, that is, exhibits a substantially vertical alignment, as shown in FIG. 2B. Thus, the surface of the common electrode 21 is modified with a linear alkyl chain R1. The first alignment film 22 is formed by applying an alignment film forming material on the substrate body 20A by a coating process such as spin coating or flexographic printing.

  As the alignment film forming material, a self-assembled compound, that is, a reactive group that is chemisorbed (bonded) to the common electrode 21 (for example, an alkoxy group that hydrolyzes to give a silanol group) and the alignment of liquid crystal molecules are regulated. A silicon-based compound having a site to be formed (for example, the R1 composed of an alkyl group having 10 to 20 carbon atoms), an organic silane, or the like is used.

The second alignment film 13 on the element substrate 10 side is composed of an inorganic alignment layer 15 and a surface layer 16 as shown in FIGS. The inorganic alignment layer 15 is formed by depositing an inorganic alignment film forming material on the substrate body 10A by the oblique evaporation method. As the inorganic alignment film forming material, SiO ₂ or silicon oxide of SiO is used.

  The surface layer 16 is formed on the inorganic alignment layer 15, and as shown in FIG. 3B, the linear alkyl chain R2 bonded by reacting with the silanol group (Si—OH) of the inorganic alignment layer 15 is bonded. And a second surface layer 16B having a linear alkyl chain R3 bonded to the silanol group of the inorganic alignment layer 15 and the silanol group of the first surface layer 16A. Yes. However, since the second surface layer 16B is directly bonded to the inorganic alignment layer 15, the first surface layer 16A and the second surface layer 16B are simply laminated. Instead, they are formed in a mixed state.

The linear alkyl chains R2 and R3 constituting the first surface layer 16A and the second surface layer 16B roughly reflect the surface shape of the inorganic alignment layer 15 formed by oblique deposition. That is, the linear alkyl chains R 2 and R 3 extend (bond) substantially along the shape of the inorganic alignment layer 15, so that they have substantially the same pretilt (alignment regulating force of liquid crystal molecules) as the inorganic alignment layer 15. It has become.
The first surface layer 16A and the second surface layer 16B are formed by subjecting the inorganic alignment layer 15 to a surface treatment with a silane coupling agent, as will be described later.

Next, a manufacturing method of the liquid crystal display device having the above configuration will be described.
First, a transparent substrate 20A made of glass or the like is prepared, and a light shielding film (not shown) and the common electrode 21 are formed thereon by a known method.
Subsequently, the first alignment film 22 is formed on the common electrode 21 to obtain the counter substrate 20. In order to form the first alignment film 22, an alignment film forming material made of a silicon compound containing a linear alkyl group (linear alkyl chain R 1) is applied onto the counter substrate 20 by a coating process such as spin coating or flexographic printing. It is done by applying to. When the alignment film forming material is applied on the common electrode 21 made of ITO as described above, the common electrode 21 is covered on the transparent substrate 20A by the reaction between the hydroxyl group on the ITO surface and a reactive group (hydrolyzing group) such as an alkoxyl group. In this state, a self-assembled monolayer (SAM) is formed.

Specifically, a SAM having an alkyl group (octadecyl group) that becomes a linear alkyl chain is applied on the common electrode 21 by applying a methanol solution of octadecyltrimethoxysilane in a N ₂ atmosphere on the substrate body 20A. Can be formed. In this way, the first alignment film 22 having an organic-inorganic hybrid structure in which the main chain skeleton is made of Si is obtained on the substrate body 20A.
As the coating process, various methods other than those described above can be employed. For example, an immersion method (dip coating method), a spray coating method, various printing methods, and an ink jet method can be employed.

Also, a transparent substrate 10A made of glass or the like is prepared, and a shielding film, a semiconductor layer, various wirings such as scanning lines and data lines (all not shown), pixel electrodes 12 and the like are formed by a known method. Subsequently, as shown in FIG. 4A, SiO ₂ is obliquely deposited on the pixel electrode 12 by a vacuum process using a vacuum film forming apparatus to form an inorganic alignment layer 15. Specifically, in the vacuum film forming apparatus, the angle (incident angle) formed between the film forming surface of the transparent substrate 10A and the incident direction of the film forming material with respect to the film forming surface is less than 90 degrees. Set. As a result, an orthorhombic crystal of a film forming material (SiO ₂ ) grows on the film formation surface, and a film having a desired oblique columnar structure (pretilt) can be formed. Thus, after forming the inorganic alignment layer 15 in 10 A of transparent substrates, surface treatment is performed to this inorganic alignment layer 15, and the element substrate 10 is formed.

In the surface treatment, first, the transparent substrate 10A on which the inorganic alignment layer 15 is formed is treated with a first silane coupling agent having a linear alkyl group (linear alkyl chain). Here, the silane coupling agent has an organic functional group and a hydrolyzable group in one molecule, thereby linking the inorganic substance and the organic substance, and improving the physical strength, durability, adhesiveness, etc. of the material. Is possible. The first silane coupling agent has a silicon atom (Si) having one organic functional group and a functional group (hydrolyzable group) that reacts with an inorganic substance. Is used.
YSiX ₃ (Formula 1)
X: a hydrolytic group bonded to a silicon atom, —OR, —Cl, —NR ₂ , etc. (where R represents an alkyl group)
Y: an organic functional group that reacts with an organic matrix, etc., and an alkyl group (—R)

The first silane coupling agent to be used may be any organic functional group having good water repellency and light resistance. Specifically, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltriethoxysilane, Octadecyltrimethoxysilane or the like can be used. In particular, in order to exhibit good liquid repellency, preferably having an alkyl group (wherein the linear alkyl group R2) long is an organic functional group (Y), decyl trimethoxysilane _{(C 10 H 21 Si (OCH} 3 ₃ ) is preferably used. In addition, in the said silane coupling agent, what changed (-OR), (-Cl), (-NR < ₂ >) etc. into the hydrolyzable group instead of the alkoxy group can also be used.

  As the surface treatment with such a first silane coupling agent, a vapor phase method is preferably employed. Specifically, the transparent substrate 10A on which the inorganic alignment layer 15 is formed and the container containing the first silane coupling agent are put in a chamber, and the inside of the chamber is a closed space. Then, by heating the inside of the chamber and promoting the evaporation of the first silane coupling agent, the vapor of the first silane coupling agent is brought into contact with the surface of the inorganic alignment layer 15 to be reacted. For example, decyltrimethoxysilane is used as the first silane coupling agent, and the inside of the chamber is heated to 175 ° C. for surface treatment. Thereby, as shown in FIG. 4B, the silanol group on the surface of the inorganic alignment layer 15 reacts with the hydrolyzable group (methoxy group) of the first silane coupling agent, and the first silane coupling agent adheres. Thus, the first surface layer 16A having a linear alkyl chain R2 (decyl group) on the surface of the inorganic alignment layer 15 is formed.

  However, even if the first silane coupling agent having the relatively long alkyl group R2 is reacted with the inorganic alignment layer 15 and adhered to the surface thereof, the surface of the inorganic alignment layer 15 is caused by steric hindrance due to the alkyl group. It is difficult to react all of the silanol groups with a silane coupling agent. Therefore, some silanol groups remain on the surface of the inorganic alignment layer 15 as unreacted silanol groups, that is, active points. In addition, since the first silane coupling agent has three hydrolyzable groups (methoxy groups) as described above, some of them are OHated to form new silanol groups, that is, the first silane. It becomes a silanol group derived from the coupling agent.

As the surface treatment for the inorganic alignment layer 15, next, the transparent substrate 10A surface-treated with the first silane coupling agent is treated with the second silane coupling agent having a linear alkyl group (linear alkyl chain). Surface treatment. As the second silane coupling agent, unlike the first silane coupling agent, one represented by the following formula 2 is used.
Y ₃ SiX (Formula 2)
In addition, each group of X and Y is the same as the said Formula 1, X is a hydrolysis group, Y is an alkyl group.

As shown in Formula 2, the second silane coupling agent has only one hydrolyzable group and the other group is an alkyl group. Specifically, trimethylmethoxysilane, vinyloxytrimethylsilane, vinyloxytriethylsilane, triethylmethoxysilane, triethylethoxysilane, octyldimethylmethoxysilane, octadecyldimethylmethoxysilane and the like can be used. In addition, in the said silane coupling agent, what changed (-OR), (-Cl), (-NR < ₂ >) etc. into the hydrolyzable group instead of the alkoxy group can also be used.

  Moreover, as this 2nd silane coupling agent, it is preferable to use what the carbon number of the linear alkyl chain is less than the carbon number of the linear alkyl chain of the said 1st silane coupling agent. This is because the second silane coupling agent does not cause steric hindrance to the first silane coupling agent attached to the inorganic alignment layer 15 and easily reacts with silanol groups remaining on the surface of the inorganic alignment layer 15. It is to do. In the present embodiment, vinyloxytriethylsilane is preferably used.

  As such a surface treatment with the second silane coupling agent, a vapor phase method is suitably employed as in the surface treatment with the first silane coupling agent. Specifically, after the transparent substrate 10A subjected to the surface treatment with the first silane coupling agent is washed and further dried, the transparent substrate 10A is treated similarly to the surface treatment with the first silane coupling agent. It puts into a chamber with the container which put the 2nd silane coupling agent, and makes the inside of a chamber closed space. Then, by heating the inside of the chamber and promoting the evaporation of the second silane coupling agent, the inorganic orientation in which the vapor of the second silane coupling agent is subjected to a surface treatment with the first silane coupling agent. The surface of the layer 15 is contacted and reacted.

For example, vinyloxytriethylsilane is used as the second silane coupling agent, and the inside of the chamber is heated to 130 ° C. for surface treatment. As a result, as shown in FIG. 3B, the silanol group remaining on the surface of the inorganic alignment layer 15 reacts with the hydrolyzable group (methoxy group) of the second silane coupling agent, and the second silane coupling. The agent adheres. The hydrolyzable group of the second silane coupling agent also reacts with the silanol group derived from the first silane coupling agent, and the second silane coupling agent adheres. Therefore, as shown in FIG. 4C, the second surface layer 16B having the linear alkyl chain R3 (ethyl group) is formed on the surface of the inorganic alignment layer 15.
Thereafter, the transparent substrate 10A subjected to the surface treatment with the second silane coupling agent is washed and further dried to obtain the element substrate 10.

Here, in the surface treatment with the second silane coupling agent, the treatment temperature, that is, the heating temperature, is set lower than the treatment temperature in the surface treatment with the first silane coupling agent. This is to prevent the compound derived from the first silane coupling agent from being detached from the inorganic alignment layer 15 when the surface treatment is performed with the second silane coupling agent. However, when such desorption hardly occurs, it is not necessarily limited to the above processing temperature conditions.
In the surface treatment with the first coupling agent and the surface treatment with the second coupling agent, a vapor phase method is employed as the treatment method, but an immersion method (dip coating method), a spray coating method, or the like. The liquid phase method may be employed.

  As described above, when the first alignment film is formed on the transparent substrate 20A to obtain the counter substrate 20, and the second alignment film is formed on the transparent substrate 10A to obtain the element substrate 10, these substrates 10, 20 are obtained. In the meantime, liquid crystal is injected by a known method to produce a liquid crystal panel. Thereafter, the polarizing plates 14 and 23 are provided to form the liquid crystal display device 1 shown in FIG. In addition, by forming such a liquid crystal display device 1, a large number of liquid crystal display elements constituting the liquid crystal display device 1 can be formed at the same time.

  According to such a manufacturing method, the inorganic alignment layer 15 formed by the vacuum process is surface-treated with the first silane coupling agent, and then the second silane coupling agent having only one hydrolyzable group. Then, a second alignment film is formed by surface treatment. Therefore, even if a large amount of silanol groups remain on the surface of the inorganic alignment layer 15 after the surface treatment with the first silane coupling agent, the surface treatment is performed with the second silane coupling agent. By reacting the second silane coupling agent with the group, the remaining silanol groups serving as active sites can be sufficiently reduced.

Further, since the first silane coupling agent has a plurality of hydrolyzable groups, a new silanol group derived from the first silane coupling agent may be formed. Since the second silane coupling agent also reacts with the silanol group derived from the ring agent, it is possible to reduce the residual silanol group serving as the active site.
Furthermore, since the second silane coupling agent has only one hydrolyzing group, this hydrolyzing group reacted with the silanol group on the SiO ₂ film surface or the silanol group derived from the first silane coupling agent. Later, no new silanol group derived from the second silane coupling agent is formed.

  Therefore, according to the manufacturing method of the present embodiment, many silanol groups remain in the second alignment film, and due to this, between the element substrate 10 and the counter substrate 20 (between the pixel electrode 12 and the common electrode 21). The voltage change with time can be suppressed. Therefore, a change in display characteristics over time can be suppressed, and thus a highly reliable liquid crystal display device (liquid crystal display element) can be manufactured.

In addition, since the alignment film (first alignment film 22) of the counter substrate 20 is formed by a coating process using a coating material, cost can be reduced.
Furthermore, since the treatment temperature at the surface treatment with the second silane coupling agent is lower than the treatment temperature at the surface treatment with the first silane coupling agent, the surface is treated with the second silane coupling agent. When the treatment is performed, it is possible to prevent the compound derived from the first silane coupling agent from being detached from the inorganic alignment layer 15, and thus it is possible to ensure the function of the linear alkyl group R2.
In addition, in the liquid crystal display device (liquid crystal display element) obtained by such a manufacturing method, the temporal change in voltage between the substrates (between the electrodes) is suppressed, so that the display characteristics over time are reduced. Changes are also suppressed and are therefore more reliable.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.
For example, although the present invention is applied to a transmissive liquid crystal display device in the above embodiment, the present invention is not limited to this, and a reflective or transflective liquid crystal display device (liquid crystal display element) and a method for manufacturing the same. It is also applicable to.
In the embodiment, the alignment film of the counter substrate 20 is formed by a coating process, and the alignment film of the element substrate 10 is formed by using a vacuum process. Conversely, the alignment film of the counter substrate 20 is formed by using a vacuum process. The alignment film of the element substrate 10 may be formed by a coating process.

[Experimental example]
As the liquid crystal panel according to the present invention, an example product and a comparative example product were manufactured by the same method as the manufacturing method of the above embodiment.
However, in the manufacture of the example product, decyltrimethoxysilane having three hydrolyzing groups is used as the first silane coupling agent, and trimethylmethoxy having one hydrolyzing group as the second silane coupling agent. Silane was used.
In the production of the comparative product, decyltrimethoxysilane was used as the first silane coupling agent, and methyltrimethoxysilane having three hydrolyzable groups was used as the second silane coupling agent.

The obtained Example product and Comparative product liquid crystal panel were each subjected to an aging test for a predetermined time.
Vcom at the start of aging and Vcom at the end of aging (after a predetermined time) were measured, and the amount of change was determined. FIG. 5 shows the obtained Vcom change amount.
As shown in FIG. 5, the example product using one hydrolyzable group as the second silane coupling agent has a smaller amount of change in Vcom than the comparative example product, and therefore between the substrates (between the electrodes). It was confirmed that the voltage change with time was suppressed.

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 10 ... Element substrate, 12 ... Pixel electrode, 13 ... 2nd orientation film, 15 ... Inorganic orientation layer, 16 ... Surface layer, 16A ... 1st surface layer, 16B ... 2nd surface layer 20 ... counter substrate, 21 ... common electrode, 30 ... liquid crystal layer

Claims (4)

A liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of opposing substrates, and an alignment film provided between the pair of substrates and the liquid crystal layer, respectively,
Forming a first alignment film having a linear alkyl chain on the liquid crystal layer side of one of the pair of substrates by a coating process;
An inorganic alignment layer is formed on the liquid crystal layer side of the other of the pair of substrates by a vacuum process, and then the inorganic alignment layer is surface-treated with a silane coupling agent to form a second alignment film. A process,
The step of forming the second alignment film includes a step of surface-treating the inorganic alignment layer with a first silane coupling agent having a linear alkyl chain, and thereafter having a linear alkyl chain, and And a step of surface-treating with a second silane coupling agent having only one hydrolyzable group.   2. The liquid crystal display element according to claim 1, wherein the carbon number of the linear alkyl chain of the second silane coupling agent is less than the carbon number of the linear alkyl chain of the first silane coupling agent. Production method.   The treatment temperature in the step of surface treating with the second silane coupling agent is lower than the treatment temperature in the step of surface treating with the first silane coupling agent. Liquid crystal display element manufacturing method. A liquid crystal display element comprising a liquid crystal layer sandwiched between a pair of opposing substrates, each having an alignment film provided between the pair of substrates and the liquid crystal layer,
A first alignment film having a linear alkyl chain formed by a coating process is provided on the liquid crystal layer side of one of the pair of substrates, and the other of the pair of substrates has the first alignment film. It has a second alignment film on the liquid crystal layer side,
In the second alignment film, an inorganic alignment layer formed by a vacuum process is surface-treated with a first silane coupling agent having a linear alkyl chain, and then has a linear alkyl chain and is hydrolyzed. A liquid crystal display element characterized by being surface-treated with a second silane coupling agent having only one decomposing group.

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